Process of diffusing metal into the surface of sheet metal



Dec. 29, 1964 M. R. COMMANDAY :ETAL 3,163,553

PROCESS OF DIFFUSING METAL INTO THE SURFACE OF SHEET METAL 2 Sheets-Sheet 1 Filed Oct. 27. 1958 Mun/c5 1?. toMmAA/oAv GEORGE MRT/A/ IN VENTOR.

Arm/mew Dec. 29, 1964 M. R.COMMANDAY ETAL 3,163,553

PROCESS OF DIFFUSING METAL. INTO THE SURFACE OF SHEET METAL Filed Oct. 27, 1958 2 Sheets-Sheet 2 Mun/cs H. GOMMZNDAY GEORGE MRT/N JNVENTOR.

Armmvsrs United States Patent 3,163,553 PROCESS OF DIFFUSING METAL IN'lt) THE SUR- FACE OF SHEET METAL Maurice R. Commanday and George Martin, Los Angeles, Callf.; said Commanday assignor, by mesne assignments, to Chromizing Corporation, a corporation of Delaware Filed Oct. 27, 1958, Ser. No. 781,824 (Filed under Rule 47(a) and 35 U.S.C. 116) 9 Claims. (Cl. 117-7) This invention has to do generally with improved methods and means for the-diffusion into sheet metal stock of a treating metal in a manner such that the treating metal is caused to diffuse into and alloy with the stock metal to impart to its surface such properties as greater hardness, corrosion or wear resistance characteristics of the alloy.

In the past, this general practice has been employed or proposed (see US. Patent 2,536,774 and British Patent 572,703) for the diffusion into ferrous metals such as steel, of such alloying metals as chromium, molybdenum, tungsten, titanium, zirconium, nickel, tantalum, cobalt, copper, beryllium, zinc and vanadium. In keeping with past practices the metal to be treated is furnace heated in contact with a comminuted mixture of the treating metal source, such as the metal or a compound or complex thereof such as a ferro-form of the metal, and a refractory material together with a halogen .source, which may be the halogen itself and/or a combined form from which the halogen is releasable as a so-called energizer for effecting transfer of the treating metal in a nonoxidizing furnace atmosphere. In practice, chromizing 'of high carbon or low carbon steel has been conducted using, typically, ferrochrome, a refractory material and a halogen source.

The present invention, contemplating the use of any of suchtreating materials adaptable for diffusion of the treating metal into sheet metal stock, isprimarily concerned with an improved method for initially contacting the sheet metal with the comminuted treating mixture for furnace heating, and with a novel form of pack resulting from that method. In this connection, the invention contemplates the making and utilizing of a pack in which the metal instead of being limited to treatment in relatively small lengths or areas, may be treated in large extended lengths and areas accommodated in one compact form in which the treating mixture is incorporated, all to advantage in saving of time and labor, efficient use of materials and furnace space, and the quality of the treated product metal.

In accordance with the invention the sheet metal stock to be treated is fed to an appropriate convolute roll winding mechanism, associated with which is suitable means forming a throat at the convergence of the feed stock with the roll being wound, and into which the comminuted treating compound or mixture is fed in a manner which preferably affords substantially uniform distribution be- I tween the roll convolutions and in quantity sufiicient for general art, depending upon the particular metals involved. V V 1 the various features and objects of the invention. a?

Patented Dec. 29, 1964 ice Well as the details of an illustrative embodiment, will be more fully understood from the following description,

of the accompanying drawings, in which:

FIG. 1 is a view showing typical roll winding and compound feeding mechanism in side elevation;

FIG. 2 is an end elevation of FIG. 1;

FIG. 3 is a fragmentary enlarged view showing the compound feeder in relation to the roll being wound;

FIG. 4 is a transverse view of the brake device taken on line 4-4 of FIG. 3;

FIG. 5 is a fragmentary enlargement of the roll being wound, illustrative of the compound delivery thereto and its accommodation between the roll convolutions; and

FIG. 6 is a perspective showing of the wound and bound roll.

First, it is to be understood that any suitable mechanism may be employed for winding the sheet metal stock in convolute roll form, and for feeding the compound between the convolutions in the manner outlined in the foregoing. Accordingly, the apparatus showings in the drawings are to be regarded merely as illustrative of a suitable mechanical means for carrying out the present method and forming the resultant convolute wound pack.

Referring first to FIGS; 1 and 2, the apparatus is shown to comprise a frame structure including a base it uprights 11 and 12 supporting horizontal members 13, all in a manner such that a roll 14 of the sheet metal to be treated is supported for rotation on the rollers 15 and has its horizontal displacement limited between rolls in and 17. Frame member 12 together with horizontal members 17 support a supply hopper 18 from which the comminuted compound 19 is delivered to the feeder, generally indicated at 26.

As it is drawn from the rotatably supported roll 14, the sheet metal stock 21 which typically may be a low carbon steel, passes through a braking device 22 and thence over a roll 23 carried by a shaft 24 to be wound on an expanding type (radially collapsible) mandrel 25 projecting centrally from a face plate or disc 126 having a shaft 26 journal ed in bearings 27 mounted on oscillatory arms 28 which may be swung on shaft 29.

Suitable provision is made to serve the dual functions of urging the rolls 25 and 45 together at substantially uniform pressure, and to permit'such progressive displacement of roll 25 as will accommodate the increasing diameter of the roll pack as it is being wound. Typically such through line 65. The constantly applied force exerted by the piston swings arms'28 and roll 25 toward roll 45 to maintain a constantv pressure at their interface below the throat 47, the piston however being displaceable downwardly within the cylinder to permit movement of roll 25 away from roll 45 in accordance with the progressive increase in diameter of the convolute pack at it is being wound.

The brake 22. is shown to comprise a pair of pressure pads 3?; bearing against the sheet 21 passing between them, i and confined between support 33 and the head 34 of a press screw 35 extending through a stationary supported threaded sleeve 36 and rotatable by handle 37 to vary the braking confinement applied to the strip 21 and therefore its resistance to advancement. The brake is so ads justed, as to tension the strip 21 in resistance to the winding pull of the drum 25, sufficiently to assure tracking and progressive compaction of the roll convolutions against the filledin treating compound.

DrumZE' is driven by motor 38 through. gear box 39,

chain 40 applied to sprocket 41 on shaft 29, and chain 42 passing over sprockets 43 and 44 respectively on shafts 29 and 26. Advancing to the drum 25, the sheet 21 passes over roll 23 mounted on shaft 24, the sheet in passing over the roll forming with the convolute roll 30 a throat 47 into which the compound 19 is dropped from the feeder 20. The latter is shown to comprise typically a roller 48 extending within the feeder housing '49 and carrying terminally an external sprocket 50 driven by chain '1 from sprocket 52 on shaft 24, roll 23 and sprocket 52 being turned by the frictional drive imparted by the sheet 21. The comminuted compound 19 passes through slot 53 in the bottom of the hopper 18, onto the roll 48 at a rate governed by the rotative speed of the roll, which in turn is governed to assure delivery of the compound into the throat -l7 in a quantity rate required for adequate filling-in betv een the roll pack convolutions.

The compound 19 is introduced to the throat 37 and distributed across substantially the width of the sheet 21, in quantity sufiicient for treatment of the contacting metal surfaces in the wound roll, the quantity of the compound and therefore the thickness of its layers at 55 in the roll, being variable in accordance with such considerations as the composition of the compound and the particular metals or combinations thereof involved in the diffusion process. As previously indicated, the layer thickness at 5'5 may be in the order of about 0.005 to 0.50 inch. Upon completion of the strip winding into the convolute roll 30, the latter may be tied and its outside convolutions held in the condition in which they are wound, by any suitable means. Typically, the completed roll pack is shown in FIG. 6 to be held against opening of its convolutions, by externally applied metal bands 56.

The roll pack thus formed may be heated in any appropriate furnace and in an inert or non-oxidizing atmosphere wider temperatures and time conditions of the order commonly employed in the conventional diffusion processes. Generally, the temperature of heating will be maintained within the range of about 1200 to 2000 F. over periods of from 4 to 6 hours.

in further reference to the treating compound 19, the latter typically may comprise a comminuted mixture of a refractory powder serving as a filler or diluent, a source of the treating metal either in elemental or combined condition, and an energizer or halogen source comprising one or more combined or elemental halogens. Suitable refractory fillers include typically tabular calcined alumina, adsorptive alumina, magnesium oxide, calcined or uncalcined kaolin and any of the inert refractory oxides. The treating metal source may consist of the metal, e.g. chromium, in powdered form, or the ferro-metal such as ferrochrome, in powdered form. The energizer, in which the halide may be fluorine, chlorine, bromine, iodine or mixtures of these, chemically may be combined halides such as the ammonium or lithium halides or the elemental halide in the case of iodine, or mixtures of these.

The following may be cited as typical examples of usable treating compounds.

Each of these compositions is usable in the described pack for the chromizing of sheet steels, and specifically 0.10 carbon steel, by heating at 1850 F. for from 4 to 16 hours.

Other metals, e.g. zirconium, beryllium, titanium (as titanium oxide), aluminum and silicon, may similarly be formulated and used with appropriate refractory filler and halogen source, although as known to those familiar with the art, the percentages may require adjustment with different treating metals, and the furnace temperatures may require limitation (e.g. around 1200 F. for aluminum and around 1600 F. for silicon) within the general range of 1200 to 2000 F. required by the metals as a class.

We claim:

1. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture containing said metal together with a halogen source and solid diluent, that includes winding the sheet metal in a convolute roll, feeding, distributing and compacting said mixture between the roll convolutions as they are being wound to thus form a roll pack, and heating the pack to diffuse the treating metal into the sheet metal.

2. The process of claim 1 in which said sheet metal is ferrous and said treating metal is chromium.

3. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture containing said metal together with a halogen source and solid diluent, that includes Winding the sheet metal in a convolute roll, feeding, distributing and compacting said mixture between the roll convolutions as they are being wound to thus form a roll pack, securing the roll to hold the convolutions against the filled-in treating metal, and heating the pack to diffuse the treating metal into the sheet metal.

4. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture containing said metal together with a halogen source and solid diluent, that includes winding the sheet metal in a convolute roll, while maintaining the sheet metal under tension, feeding, distributing and compacting said mixture between the roll convolutions as they are being wound to this form a roll pack, and heating the pack to diffuse the treating metal into the sheet metal.

5. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture containing said metal together with a halogen source and solid diluent, that includes winding the sheet metal in a convolute roll, feeding, distributing and compacting said mixture between the roll convolutions as they are being wound to thus form a roll pack, and heating the pack to a temperature between about 1200? F. and 2000 F. to diffuse the treating metal into the sheet metal.

Ammonium chloride 0.25

6. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture containing said metal together with a halogen source and solid diluent, that includes winding the sheet metal in a convolute roll, while maintaining the sheet metal under tension, feeding, distributing and compacting said mixture between the roll convolutrons as they are being wound to thus form a roll pack, securing the roll' to hold the convolutions against the filled-in treating metal, and heating the pack to a temperature between about 1200 F. and 2000 F. to diffuse thetreating metal into thesheet metal.

7. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture, that includes winding the sheet metal in a convolute, roll,.feeding, distributing and compacting said mixture'between the'roll convolutions as they are .being wound to thus form a roll pack, and heats the pa to a te p a e, between about 1200 F.

5 and 2000 F. to diffuse the treating metal into the sheet metal, said sheet metal being ferrous and said mixture comprising in addition to said treating metal, a refractory material and a halogen energizer source.

8. The process of diffusing into the surface of sheet metal a treating metal from a source contained in a comminuted treating mixture, that includes Winding the sheet metal in a convolute roll, while maintaining the sheet metal under tension, feeding, distributing and compacting said mixture between the roll convolutions as they are being Wound to thus form a roll pack, securing the roll to hold the convolutions against the filled-in treating metal, and heating the pack to a temperature between about 1200 F. and 2000 F. to diifuse the treating metal into the sheet metal, said sheet metal being ferrous and said mixture comprising in addition to said treating metal,

5 a powder refractory material and a halogen energizer source.

9. The process of claim 8, in which, said sheet metal is ferrous and said treating metal is chromium.

References Cited in the file of this patent UNITED STATES PATENTS 1,312,716 Wise Augp12, 1919 1,857,215 Ruder May 10, 1932 1,891,235 Lawton et al. Dec. 20, 1932 2,443,663 Rider et al. June 22, 1948 2,836,513 Samuel May 27, 1958 FOREIGN PATENTS 160,812 Australia Jan. 28, 1955 

7. THE PROCESS OF DIFFUSING INTO THE SURFACE OF SHEET METAL A TREATING METAL FROM A SOURCE CONTAINED IN A COMMINUTED TREATING MIXTURE, THAT INCLUDES WINDING THE SHEET METAL IN A CONVOLUTE ROLL, FEEDING, DISTRIBUTING AND COMPACTING SAID MIXTURE BETWEEN THE ROLL CONVOLUTIONS AS THEY ARE BEING WOUND TO THUS FORM A ROLL PACK, AND HEATING THE PACK TO A TEMPERATURE BETWEEN ABOUT 1200*F. 